Optical character recognition



A ri 8, 1969 A' W. LOHMANN 3]437,824

0PTICAL CHARACTER RECOGNTON Filed oct. 16 1964 (FRAUNHOFER PLANE) FIG.2

ZNVENTOR ADOLF W LOHMANN ATTORNEY p 1969 A' W. LOHMANN v 3,437,824

OPTICAL CHARACTEB)REO0GNITION F1ed oct -16' 1964 Sheet a of 2 VARIABLE ATTENUATOR a4 OUTPUT What iS claimed iS:

1. AI1 ptical character Tecognition system c0mprising:

a nrst optical means for forming a Fraunhofer difaC tion pattern Of a rSt Chafacter;

means for rand0mizing the phase of the light 0f said diractiOn pattern, Said rand0mizing means being p0 Sitioned at the diTacti()n )attern;

Ineans for c01limating the light from Said Tand0mizing means and directing the light to a Second character;

Second 0ptical means for forming a Fraunh0er dif fraction pattern Of the light received fron1 Said Second character; and

means for detecting the intensity of the 1ight at the center of the diifraction attern fOrned by Said sec- Ond optical means;

Whefeby the Similarity or dissimilarity between Said Second characters can be detected z ^n optical character rec0gnition System c0mPTiSng:

a first optica1 n1eans f01 f0Ining a Fraunh0fer dirac tion pattern Of an unkn0wn character;

neans for Tand0mizing the phase 0f the light Of Said diffraction pattern, Said Tand0mizing means being positioned at the difactiOn pattern;

means for c011inlating the light from said randornizing means and directing the 1ightto a' I)1lraity Of second characters, each Second character being dieTent;

a Plurality 0f Second optical nleans, each Second 0ptical lneans f0rming a Fraunh0fer diractiOn pattern of the light received ffom one 0f Said diferent Sec- Ond characters; and

detecting means for detecting the intensity Of the light as the center Of the diractiOn pattern forn1ed by each of Said Second optical n1eans;

vvhereby Said detecting IIleans indicates the particular Second character vvhich is the same as said unknown character 3 A1 0ptical character rec0gnition system con1prising:

a rSt optica1 T[leans for forIning a Fraunhofer diffraction Pattern of a first charactef;

nleans for randomizing the hase of the light of Said diifracti0n pattern, Said rand0Inizing meanS being 1)( sitioned at the diffraction pattern;

means for c011imating the light from Said Tand0mizing means and difecti1g the light tO a plurality of Second characters, each Second character being dieTent;

a high ffequency difffaction gating Superinp0sed on each of said Second characters, Said diTactiOn grat ing being different for each of Said Second characters;

Second optical means fO f0rming a Fraunhofer dif fraction pattern of the light Teceived f1()IT1 Said plu Tality 0f second characters having diTactiOn gratings superimp0sed thereon; and

a plurality of detecting means, equal in number to tle nunlbef Of diffefent gratings, each detecting means cated at the center of one Of the TSt Or higher order diffraction Spots generated ffom a dieTent one of the gratings, for detecting the intensity of the light at the centel Of Said Sp0t;

Whefeby the siInilarity or dissinilarity between Said first character and each of said second characters can be detected 4- The device recited in claim 1 Wherein Said n1eans for randomizing the hase 0f the light c0mprises a plate 0f ground glass.

5' Ihe device recited in clain1 2 Wherein Said nleans for rand0nizing the hase of the 1ight c0mprises a plate of ground glass' 6. 'l^he device recited in CaiIn 3 vvherein Said Ineans for randomizing the hase of the light Comprises a plate Of ground glass 7' An optical character Tec0gnition system c0mprising:

first, Second, third and fourth lenses p0sitioned a10ng an optical axis;

a light source )0Siti()ned on said optical axiS at the front f0cal plane of Said i lrstle1s;

each lens being Spaced fron1 the preceding lens by the Sum of the focal lengths Of Said lenS and the Preceding lens S0 that the light between Said nrst and sec- Ond lenses iS c011imated and the light between Said third and fourth lenses is collimated;

a late of ground glass positioned in the Fraunhofer plane between said Second and third lenses for randomizing the phase 0f the light passing through said plane;

a record having a i lrst optically visible character there- 0n positioned between Said first and Second lenses vvhereby a diraCti0n pattern Tepresentative 0f said character is generated in Said Fraunh0fer plane; and

an identification Inask having a Second optically visible character thereon positi0ned between Said third and fouTth lenses;

Whereby a diifraction pattern iS generated in the Fraun hofer plane beyond said fourth lens Which indicates vvhether Said iirst character is the same as Said Sec- 0nd character 8. An optical character recognition System Comprising;

first, Second, thifd and fouTth lenses p0sitioned along an optical axis;

a point light Source p()siti0led on Said optical axis at the front focal p0int of Said Hrst lens;

each lenS being Spaced from the preceding lens by the Sun1 Of the focal lengths of said lens and the preceding lens S0 that the 1ight between Said iilst and Sec- 0nd lenses iS couimated and the light between Said third and fourth lenses iS couimated;

a )1ate Of ground glass p05itioned in the Faunh0fer plane between Said Second and third lenses;

a rec0rd having a rSt optically visible character thereon 0Sitioned between said H1St and Second lenses Whefe by a diffraction pattern representative of said character is generated on said plane of ground glass; and

an identiCatiOn mask having a plurality of second optically visible characters thereon p0sitioned betvveen said third and fourth lenses, each Second charactel being different; and

a high frequency diractiOn grating Superimp0sed on each of Said second characters, Said diraCti()n grating being different for each Of Said Second characters;

Whereby a lurality of diffraction attems are gen erated in the Fraunhofer plane beyond said f0urth lens for each second character, each of Said dirac tion patterns being Physically separated, the intensity Of light at the cente1 of each character indicating whether said first charactet iS the Sane as the aSSO- ciated Second character lefeenceS (:ited

UNITED STATES PATENTS 3,196,39Z 7/196 HOTwitz et al 340146.3

U.S. DEPARTMENT 0F C0MMERCE PATENT 0FFICE washington,).c 20231 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 457 824 Ado 1 f W Lohmann A ri1 8 1 t is certified ha error a' )earS in the above identified aen and ha saic1 Jeters Paen are hereby corrected as shown b e1ow Co1u! 1n 11, 1ine 17 before "Second" insert first and 11ne 52 "as" Shou1d read at 1ine 46 atin Shou1d read ratin Si ned and Sealed th1s 7th da of 0ctober 1969.

(SEAL) Attest:

WILLIAM E. SCHUYLER,

Edwar(l M. Flecher, JT

(:0Inissi0ner of Patel Attesting 0fficer 

1. AN OPTICAL CHARACTER RECOGNITION SYSTEM COMPRISING: A FIRST OPTICAL MEANS FOR FORMING A FRAUNHOFER DIFFRACTION PATTERN OF A FIRST CHARACTER; MEANS FOR RANDOMIZING THE PHASE OF THE LIGHT OF SAID DIFFRACTION PATTERN, SAID RANDOMIZING MEANS BEING POSITIONED AT THE DIFFRACTION PATTERN; MEANS FOR COLLIMATING THE LIGHT FROM SAID RANDOMIZING MEANS AND DIRECTING THE LIGHT TO A SECOND CHARACTER; SECOND OPTICAL MEANS FOR FORMING A FRAUNHOFER DIFFRACTION PATTERN OF THE LIGHT RECEIVED FROM SAID SECOND CHARACTER; AND MEANS FOR DETECTING THE INTENSITY OF THE LIGHT AT THE CENTER OF THE DIFFRACTION PATTERN FORMED BY SAID SECOND OPTICAL MEANS; WHEREBY THE SIMILARITY OR DISSIMILARITY BETWEEN SAID SECOND CHARACTERS CAN BE DETECTED. 